linux-kernel - Re: [PATCH 00/19 v2] Improve IRQ remapping abstraction in x86 core code

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Date:	Sun, 26 Aug 2012 21:17:49 +0200
From:	Sebastian Andrzej Siewior <sebastian@...akpoint.cc>
To:	Joerg Roedel <joerg.roedel@....com>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org, joro@...tes.org,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Yinghai Lu <yinghai@...nel.org>
Subject: Re: [PATCH 00/19 v2] Improve IRQ remapping abstraction in x86 core
 code

On Mon, Aug 20, 2012 at 03:55:46PM +0200, Joerg Roedel wrote:
> Please review.

Finally. Usually you don't add/change code but you just move common
irq remapping pieces out of geric io-apic code and put them in once place. I
think it would be good, if you would note this in the description of your
patch.
Altogether it makes a good impression.

After browsing through the new functions in irq_remapping_modify_x86_ops() I
see that some of them test for "remap_ops" which is pointless because you don't
call irq_remapping_modify_x86_ops() if it is not the case. This also goes mostly
for irq_remapping_enabled.
The only reason when you can disable (or say irq_remapping_disable() is
called) is in the suspend path. And the remap is enabled again in via
irq_remapping_reenable() in resume. Now if this goes wrong what is next? You
don't even return an error if the callback is missing. The variable
irq_remapping_enabled does not save your ass here because some function
behave now different.

But back to the realisitic world: If something goes wrong in resume and you
can't re-enable irq remapping, the system is not really useable or is it (even
before your series)?

> Thanks,
> 
> 	Joerg
> 

Sebastian
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